2x4W Stereo Tube Amplifier Circuit

stereo tube amplifier circuitThis 2x4W stereo tube amplifier circuit is built not using transistors, but with a tube. With a circuit that looks like in the picture, this amplifier can generate 4 watts power for each channel. Amplifier circuit with an electric tube is known to have a better quality than use the transistor power amplifiers.

As seen in the image, this tube amplifier circuit consists of two tubes per channel. Which first vacuum tube (6SQ7) serves as first stage amplifier(preamp), which will amplify from the input signal to be enough to be fed to the amplifier final level.

6V6 GT tube serves as the final stage amplifier, which is output level will be connected to oudspeaker via an impedance transformer. This amplifier circuit requires a DC supply voltage, 5Y3 tube serves as a rectifier diodes with good quality.

2x4W Stereo Tube Amplifier Circuit Components list:

C1, C4 = 200pF/600v
C2, C5 = 47nF/600v
C3, C6 = 22uF/25v
C7 = 47uF/450V
C8 = 33nF/450V
C9 = 10nF/1400v

R1A & B = 500KΩ Dual gang Potentiometer
R2, R6 = 1MΩ 1/2W
R3, R7 = 470KΩ 1/2W
R4, R8 = 220KΩ 1/2W
R5, R9 = 330Ω, wire-wound or metal oxide 2W
R10 = 750Ω, wire-wound 20W

Audio Output Transformer T2, T3
Primary (impedance) = 3300 Ω @ 400 cycles
Secondary (impedance) = 4 or 8 Ω @ 400 cycles

Power Transformer, T1
Primary = 117v 60 cycles
Sec. 1 = 600v CT @ 80mA
Sec. 2 = 5v @ 2A
Sec. 3 = 6.3v @ 4A

5Y3-GT – Full-wave vacuum rectifier

2x4W Stereo Tube Amplifier Circuit Notes:

  • To produce the best sound quality, efficiency of the speakers will affect the audio quality produced. For that use a speaker that has a maximum power of 90dB / Watt.
  • Do not forget hook-up wire, sockets, switches, and Also a chassis or circuit board. All the tubes must be use socket.
  • Resistor R10 will be very hot during amplifier circuit operated, for that conditioning your R10 locations so that all the heat can be spread out well.
  • A choke coil with a DC resistance approximate to 750 ohms may possibly be substituted for R10.